This invention relates to providing conventionally manufactured bags with a resealing mechanism and to reclosable bags in general. In particular, this invention relates to a method and apparatus for attaching a resealable closure to a bag in a form, fill, and seal process.
There are presently a multitude of products on the market whose usable life is dependent upon protection from exposure to air. These products include cereals, snack chips, candies, coffee, and the like. Because these products generate a widespread demand for airtight containers, numerous seals, packages, and package manufacturing methods have been provided. Many of these prior packages employ interlocking profile fasteners as a means of allowing resealable access to an airtight container.
U.S. Pat. Nos. 4,812,074 and 4,601,694 disclose material and apparatus for making bags having reclosable zipper profiles. In these devices, the zipper is fully integrated into the bag and is a part of the bag's primary sealing mechanism. The patents also disclose the application of an interlocking profile fastener to the bag in a direction parallel to the direction that the bag web material travels during the manufacturing process.
U.S. Pat. No. 4,909,017, et al. discloses a method of making a form fill bag having a reclosable fastener thereon. During the manufacturing process reclosable fasteners are attached to the bag in a direction perpendicular to the flow of the web material.
Reclosable plastic zippers have also been applied to bags during the form, fill, and seal process in a direction parallel with the travel of the web material of the bag. U.S. Pat. No. 4,709,533 discloses a method and apparatus for forming a vertical tubular form fill package. A plastic zipper and a thin seal form the spine of the bag. A similar method and apparatus is disclosed in U.S. Pat. No. 4,355,494 where the two sides of the interlocking profile fastener are applied to the bag independently in a direction parallel with the flow of the web material and are pressed and sealed together as the bag travels over the form, fill, and seal apparatus.
The aforementioned methods and apparatus suffer from a number of drawbacks. In those methods and devices that utilize an interlocking profile fastener as the sole sealing means for the package, a considerable amount of leakage can occur during the period of time when the product is being shipped and placed on the shelves in stores. Likewise, in those devices that utilize the combination of an interlocking profile fastener and an outer pilfer protection seal there is a higher likelihood of failure of the airtight seal of the bag than there is for a bag manufactured in a conventional form, fill, and seal process. Furthermore, devices that do not provide any type of pilfer protection may be tampered with at any point prior to the sale of the product.
A further drawback of the existing methods of applying resealable closures is the fact that most manufacturing plants that presently utilize a conventional form, fill, and seal apparatus would need to purchase new equipment or retool their own equipment to add an interlocking profile fastener seal to the form, fill, and seal bag. The degree of retooling to accomplish this type of change may be considerable. It would be advantageous, therefore, to provide a means of attaching interlocking profile fasteners to packages as a part of the conventional form, fill, and seal process in a way that requires a minimum of retooling.
There have also been many inventions relating to manufacture of resealable closure mechanisms for application to existing packages. These inventions include a zipper closure with unitary adhesive cover sheet for selective attachment along an elongated opening in a preexisting container. The closure can be purchased by a consumer and applied to a package after a slit has been cut in the package. Likewise, a tape carried precut zipper for attachment to the mouth end of a bag has also been proposed.
The present invention employs a resealable closure that can be applied at any location on an existing bag. The present invention also contemplates a method and apparatus for the application of a precut zipper that can be readily integrated into a method and apparatus of producing form, fill, and seal bags.